Common name(s): California armina

Armina californica, 6.5 cm long, from 6m depth in Burrows Bay.
Photo taken at Shannon Point Marine Station

(Photo by: Dave Cowles August 2006)

Description: This nudibranch has white
longitudinal ridges on a brownish background. It has a white or cream
line outlining the edge of the dorsum. Its anus is on the right side
of the body, on a papilla in a groove between the dorsum and the foot (photo).
The gills are also located in this groove. It has no dorsal outgrowths
except for the rhinophores. The rhinophores have longitudinal grooves
in the clavus and project anteriorly out of a notch at the front of the
mantle (photo). Length to 7 cm.

How to Distinguish from Similar Species:
This species is very distinctive. No other local species has the
combination of the anus on the right side, longitudinal white ridges on
the dorsum, and no cerata.

Geographical Range: Gulf of Alaska
to Panama

Depth Range: Mostly subtidal, 1 to
230 m

Habitat: Sandy bottoms

Biology/Natural History: This species
eats sea pens such as Ptilosarcus
gurneyi. (or on sea pansies such as Renilla kollikeri farther
south where those grow). May be largely buried in the sand with primarily
the rhinophores projecting above the surface of the sand. Eggs are
laid in a pale pinkish-brown spiral chain of capsules.

According to Baltzley et al., (2011),
many gastropods, including this species, have a special network of
pedal ganglia in their foot which assists in crawling. The two main
neurons involved produce pedal peptides which elicit an increase in the
rate of beating of cilia on the foot, resulting in crawling.

This species has a deep groove along the sides between the wide flap
of the dorsum and the wide flap of the foot. Here the groove on the
left side can be clearly seen as the animal turns.

This species has its anus on a prominent papilla on the right side,
in a groove between the flaps of the dorsum and the foot. The view
above shows the groove on the right side of the animal, with the anus to
the left (posterior) and the gonopore to the right (anterior)

This
species can crawl upside-down along the surface film of the water, as
shown by this individual crawling along the surface film of one of our seawater tanks, about 20 cm above another individual crawling along the bottom. Photo by Dave Cowles, August 2015